What’s New in Gastrointestinal Imaging – March 2022

6 months ago

Gastrointestinal Imaging ACORE

Correlation and prognostic value of CT-detected extramural venous invasion and pathological lymph-vascular invasion in colon cancer. Guan, Z., Zhang, XY., Li, XT. et al. Abdom Radiol 47, 1232–1243 (2022). https://doi.org/10.1007/s00261-022-03414-7

 

For patients with colon cancer, radical surgical resection is the primary treatment method for local disease control. Patients with high risk colon cancer may receive neoadjuvant therapy, which has been shown to increase the resection rate and benefit survival of certain patient groups. One of the high risk factors in colon cancer that may lead to consideration for neoadjuvant therapy is lymph-vascular invasion (LVI). Lymph-vascular invasion can be subdivided into lymphovascular or “small vessel” invasion, and venous or “large vessel” invasion. Pathological extramural venous invasion (EMVI) leads to a greater risk of blood metastasis and a worse prognosis. While only being one component of LVI, EMVI is the only part of LVI that is detectable on CT imaging. This study explores the association between CT detected EMVI (ctEMVI) and LVI, and analyzed the prognostic value of EMVI. The authors enrolled 448 patients with biopsy confirmed colon adenocarcinoma who underwent contrast enhanced CT prior to resection and had regular follow up after surgery. 64 patients were found to have ctEMVI, and 127 patients found to have LVI on pathology. Sensitivity, specificity, positive predictive value and negative predictive value of ctEMVI for evaluating LVI were 29.1%, 91.6%, 57.8%, and 76.6%. ctEMVI and LVI positive status were both found to be independent risk factors for overall survival and metastasis free survival. In LVI positive patients, ctEMVI positive status was a significant predictor for both overall survival and metastasis free survival, with ctEMVI patients having a worse prognosis than ctEMVI negative patients. In LVI negative patients, ctEMVI was not a significant predictor for overall survival or metastasis free survival. These associations indicate that LVI positive patients with ctEMVI need active treatments. The findings of this study show that preoperative ctEMVI could accurately screen high risk colon cancer patients and indicate prognosis that previously would have to wait until after surgery, and identify patients that may benefit from neo adjuvant therapy.

 

Primary omental torsion in children: single-center experience of 17 cases. Chen, F., Liu, J., Fan, F. et al. Abdom Radiol47, 1291–1297 (2022). https://doi.org/10.1007/s00261-022-03445-0

 

Primary omental torsion is a rare cause of abdominal pain in children that can be misdiagnosed due to overlap of symptoms with other causes of abdominal pain in children. The most classic symptom is sudden onset constant right side abdominal pain with slower progression than the pain due to acute appendicitis, and fever or GI symptoms such as vomiting or diarrhea are usually not seen. POT is more common in males and in overweight or obese patients. Omental torsion in adults is usually secondary to a mass or previous surgery. Treatment is usually operative, with excision of the twisted omentum. Classic CT findings are a fat density ovid mass with surrounding fat stranding, a vascular pedicle, and the whirl sign resulting from twisting of omental vasculature. Even with these findings preoperative diagnosis is challenging, with an estimated preoperative diagnosis rate of only about 10%. In this study, 17 cases of primary omental torsion in pediatric patients at a single children’s hospital were analyzed for age, sex, lab values including WBC and CRP, BMI and clinical symptoms, and CT findings. Of the 17 patients, 16 were male, 4 had fever and 2 had vomiting. 9 patients had elevated WBC count, 14 had elevated CRP levels. 5 patients had right upper abdominal pain, 6 had right middle abdominal pain, 5 had right lower abdominal pain, and 1 patient had periumbilical pain. 5 cases had a low-intensity inflammatory mass on ultrasound (29.41%). 16 of the 17 patients were overweight or obese. CT findings were as follows: Density of abdominal mass ranged from -70 to -46 HU, consistent with fat. All 17 patients had a fatty mass corresponding to the region of abdominal pain. The most common location was anterior to the right colon, seen in 10 patients. 5 patients had whirl sign. 8 patients had pelvic fluid. 5 cases were initially diagnosed as acute appendicitis and 12 were correctly diagnosed as omental torsion (70.59% correct diagnosis rate). All patients underwent laparoscopic resection and 1 patient had recurrence 8 months after surgery. This article is an excellent reference to help guide radiologists in the diagnosis of primary omental torsion.

 

Machine learning analysis for the noninvasive prediction of lymphovascular invasion in gastric cancer using PET/CT and enhanced CT-based radiomics and clinical variables. Lijing Fan, Jing Li, Huiling Zhang, et al. Abdominal Radiology 47, 1209-1222 (2022)

Gastric cancer is the fifth most common malignant tumor in the world, and the third leading cause of cancer death. Surgery is the best treatment for early gastric cancer, with adjuvant chemotherapy improving the efficacy in advanced cases. Lymphovascular invasion is an independent risk factor for patient prognosis, and patients with positive LVI have a higher rate of recurrence and lower overall survival than LVI negative patients. Accurate assessment of a patients LVI status is an important prognostic predictor, and can guide clinical decision making, but is currently primarily detected postoperatively on pathologic examinations with very limited ability to diagnose pre-operatively. There are no significant imaging features of LVI, however current imaging techniques show promise in assessment of LVI. Dynamic enhanced CT can effectively assess tumor angiogenesis, and 18F-FDG PET/CT can be used to assess the metabolic activity of tissues. The authors of this study investigated the value of PET/CT radiomics and clinical variables in preoperative prediction of LVI status in patients with gastric cancer. 91 patients with gastric cancer and histologically confirmed LVI status who had contrast enhanced CT or PET/CT prior to surgery were retrospectively recruited. Models with three different machine learning classifiers using clinical models to predict LVI status showed AUCs of 0.742, 0.706, and 0.690, and predictive models using imaging features showed AUCs of 0.849, 0.778, and 0.810. Combined clinical and imaging models to predict LVI status showed AUCs of 0.944, 0.929, 0.921. These results show that LVI status of gastric cancer could be accurately predicted by a model combining radiomic features in combination with clinical variables.

 

The utility of spectral Doppler evaluation of acute appendicitis. Bakhshandeh, T., Maleknejad, A., Sargolzaie, N. et al.Emerg Radiol 29, 371–375 (2022). https://doi.org/10.1007/s10140-021-02010-4

 

The incidence of appendicitis is increasing in the USA, and ultrasound can be an accurate and cost effective diagnostic tool. When gray-scale examination is indeterminate, color Doppler can be a helpful adjunct. Previous research has no found no difference in vascularity between normal and inflamed appendices, and there can be significant overlap in the color Doppler assessment of normal or inflamed appendices. Recent research suggests spectral Doppler can be used as a reliable indicator of inflammation, although reliable diagnostic cut-off points have not been established. The authors of this study aimed to establish diagnostic cut-off values for acute appendicitis using Spectral Doppler, by comparing Doppler results with the pathology findings of patients who underwent appendectomy for suspected appendicitis. In this study, patients at two different hospitals with suspected appendicitis following assessment by a surgical specialist underwent ultrasound. Patients were only included if a borderline appendix size of 6-8 mm outer diameter was found, and if gray-scale US was inconclusive. Patients underwent graded compression ultrasound with color and spectral Doppler, and Peak systolic velocity (PSV) and Resistive index (RI) were measured. Patients were then divided into a suspected appendicitis group, and underwent surgery, or a non-appendicitis group. 152 patients met inclusion criteria. A cut off value for RI was found to be 0.49 (sensitivity 90.5% and specificity 86%), and cut off for PSV was 9.60 (sensitivity 94.7% and specificity 94.7%). AUC values were used to compare the diagnostic values of the RI and PSV indices, and were both found to have statistically significant AUC for predicting pathological outcomes, AUC 0.92 for RI and AUC 0.96 for PSV. The performance of RI versus PSV was not statistically different when compared to each other. These findings show that spectral doppler can provide valuable criteria for improving the accuracy of appendicitis diagnosis in borderline cases.

Tumor enhancement ratio on preoperative abdominal contrast-enhanced CT scan for predicting recurrence risk in stage II colon cancer. Yao Ye, Wei Lu, Qun Deng, et al. Abdominal Radiology 47, 1265-1275 (2022)

Colorectal cancer has the highest incidence and highest mortality of digestive system carcinomas across the world. Stage II colon cancer is primarily treated with surgical resection, however these cancers can often recur given high risk features such as lymphatic or vascular invasion, positive margins, and poorly differentiated histology. High risk patients can benefit from adjuvant chemotherapy, however, identifying which high risk patients may benefit is ambiguous with inconsistent findings in previous studies. The authors of this study aimed to construct a model for predicting recurrence risk of stage II colon cancer based on tumor enhancement ratio (TER) on contrast enhanced CT. Tumor enhancement ratio is the tumor attenuation value in the contrast enhanced phase divided by the tumor attenuation in the non-contrast chase, and represents the regions functional vascularity. Higher TER is considered a prognostic indicator for renal cell carcinoma and gastric cancer, and has been shown to be a poor prognostic indicator in stage II colon cancer. 282 patients with high risk stage II colon cancer were retrospectively analyzed. A TER cut-off value of 1.83 was found to be a significant predictor of poorer prognosis, and was found to be a significant predictor of high risk for recurrence. These findings provide another tool to guide clinical decision making in patients with high risk colon cancer.

 

 

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